CVE-2026-55899: Microsoft Excel Remote Code Execution Vulnerability
Published Jul 14, 2026
·Updated
Microsoft Excel Remote Code Execution Vulnerability
Other sources
Stack-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
— Microsoft
Affected Software
29 affected componentsFixes available
Microsoft Excel
Microsoft 365 Apps for Enterprise<https://aka.ms/OfficeSecurityReleases
https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2024 for 32-bit editions<https://aka.ms/OfficeSecurityReleases
https://aka.ms/OfficeSecurityReleases
Microsoft Office 2019 for 64-bit editions<https://aka.ms/OfficeSecurityReleases
https://aka.ms/OfficeSecurityReleases
Microsoft 365 Apps for Enterprise<https://aka.ms/OfficeSecurityReleases
https://aka.ms/OfficeSecurityReleases
Microsoft Office Online Server<16.0.10417.20175
16.0.10417.20175
Microsoft Office 2019 for 32-bit editions<https://aka.ms/OfficeSecurityReleases
https://aka.ms/OfficeSecurityReleases
Microsoft Excel 2016<16.0.5561.1001
16.0.5561.1001
Microsoft Office LTSC 2024 for 64-bit editions<https://aka.ms/OfficeSecurityReleases
https://aka.ms/OfficeSecurityReleases
Microsoft Office 365 for Mac<16.111.26071215
16.111.26071215
Microsoft Excel 2016<16.0.5561.1001
16.0.5561.1001
Microsoft Office LTSC for Mac 2024<16.111.26071215
16.111.26071215
Microsoft Office LTSC 2021 for 64-bit editions<https://aka.ms/OfficeSecurityReleases
https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2021 for 32-bit editions<https://aka.ms/OfficeSecurityReleases
https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC for Mac 2021<16.111.26071215
16.111.26071215
Microsoft 365 Apps
Microsoft 365 Apps
Microsoft Excel=2016
Microsoft Excel=2016
Microsoft Microsoft 365 Macos
Microsoft Office 2019
Microsoft Office 2019
Microsoft Office 2021
Microsoft Office 2021
Microsoft Office 2021 Macos
Microsoft Office 2024
Microsoft Office 2024
Microsoft Office 2024 Macos
Microsoft Office Online Server<16.0.10417.20175
Remediation
Event History
Jul 14, 2026
CVE Published
via Microsoft·02:00 PM
Data Sourced
via Microsoft·02:00 PM
DescriptionSeverityWeakness
Data Sourced
via Microsoft·02:00 PM
Affected Software
Updated
via Microsoft·02:00 PM
Description
CVE Published
via MITRE·05:05 PM
Data Sourced
via MITRE·05:05 PM
DescriptionSeverity
Data Sourced
via NVD·05:17 PM
RemedyDescriptionSeverityWeaknessAffected Software
Frequently Asked Questions
1
What is the severity of CVE-2026-55899?
The severity of CVE-2026-55899 is rated high with a score of 7.8.
2
What vulnerability does CVE-2026-55899 describe?
CVE-2026-55899 describes a remote code execution vulnerability in Microsoft Excel due to a stack-based buffer overflow.
3
How do I fix CVE-2026-55899?
To fix CVE-2026-55899, you need to apply the available patch for the affected Microsoft Excel software.
4
Which software is affected by CVE-2026-55899?
CVE-2026-55899 affects Microsoft Excel, Microsoft 365 Apps for Enterprise, Microsoft Office Online Server, and various versions of Microsoft Office.
5
What type of vulnerability is CVE-2026-55899 categorized as?
CVE-2026-55899 is categorized as a buffer overflow vulnerability related to input validation.